Coagulation of sulfur dioxide resin latices to produce a coagulum in crumb or granular form



UNITED STATES Patented Aug. 10, 1954 Willie W. Crouch, Bartlesville,kla., assignor to Phillips Petroleum Company, a corporation of PATENTOFFICE Delaware No Drawing. Application April 28, 1949, Serial No.90,275

22 Claims.

This invention relates to the production of synthetic resinous materialsformed by reaction between sulfur dioxide and one or more unsaturatedorganic compounds.

This invention pertains primarily to an improved method of coagulatingsuch a resin when produced by polymerization in an aqueous emulsion.

It has been well known for a number of years that sulfur dioxide willreact with numerous unsaturated organic materials to formheteropolymeric resinous products. Apparently the resin is produced fromequimolar quantities of sulfur dioxide and the unsaturated organicmaterial. The reaction appears to take place only in the liquid phaseand it will proceed in the absence of catalysts only in the presence ofactinic light, or it will proceed in the presence of any one of a largenumber of catalytic materials, most of which appear to have oxidizingproperties, in the dark or in the light. Some of the more importantcatalysts for promoting this reaction are oxygen, hydrogen peroxide,ozone, various nitrates such as silver and lithium nitrates, nitrites,persulfates, chlorates, perchlorates, ascaridole, ozonized olefins, etc.Organic compounds which enter into the formation of such resins includemono-olefins, cyclo-olefins, substituted aliphatic olefins such asstyrene, diolefins such as butadiene, isoprene, cyclohexadiene, and thelike, acetylenes and polyfunctional unsaturated compounds such as allylalcohol, vinyl, acetate, allyl ethyl ether, o-allylannisole,o-allylphenol, p-bromoallylbenzene, methyl undecylenate, undecylenylalcohol, undecylenio acid, etc. When mixtures of such unsaturatedorganiccompounds are used, the resulting resin appears to have been formed by acopolymerization of the unsaturated compounds with sulfur dioxide sinceits properties do not correspond to blends of resins produced from theindividual unsaturated organic compounds and often have properties whichare superior to any one of the resins produced from the individualunsaturated compounds. For many of the unsaturated compounds there appears to be a "ceiling temperature above which the reaction does nottake place, and in such instances it is necessary to conduct theresin-forming reaction at a temperature below the ceiling temperatureand, when forming the resin from a mixture of organic unsaturatedcompounds, it appears desirable to conduct the reaction at a temperaturebelow the ceiling temperature of the material having the lowest ceilingtemperature. The resin-forming reaction is somewhat exothermic andgenerally some provision must be made for removing the heat of reaction.All of these features are more fully described in the literature.

The resins heretofore produced have generally been formed in thepresence of only a moderate excess of sulfur dioxide and have beenrecovered as solid materials possessing a horn-like appearance or havinga porous expanded form. These materials are tough and diflicult tohandle. In order to secure successful commercial products it has beennecessary to grind these mechanically in order to form a finely dividedmaterial, thus facilitating removal of occluded impurities. Even whenground to a fine powder, it has often been diflicult to removecompletely all of the occluded impurities, such as uncornbined reactantsand other materials either present in the reactants as charged to theprocess or introduced in processing and handling the resin. In someinstances it appears that the grinding procedure results in theintroduction of minute quantities of metallic impurities which aifectthe clarity and general appearance of the molded products. Further, thegrinding procedure develops undesirable heat which tends to soften theresin and cause the ground particles of resin to fuse, thus increasingthe diiilculty of the removal of impurities and in some instancesresulting in an unsatisfactory molding powder because of particle size.Also, even if the grinding operation results in a satisfactory, finepowder, the removal of occluded impurities is difiicult and expensive.

More recently a method has been found, and developed, whereby anunsaturated organic material and sulfur dioxide are caused to react toproduce resinous products of varied properties and wide adaptability,said products being readily freed from unreacted reactants and otherimpurities. The process comprises reacting the unsaturated compound andsulfur dioxide in aqueous emulsion in the presence of suitable catalystsand emulsifying agents. When the reaction is carried out in aqueousemulsion the material remains in a fluid condition and can be agitatedreadily, thus maintaining adequate contact of the reactants at allstages of the conversion. The resinous product, which is obtained in theform of an emulsion, can be stripped with steam to remove unreactedsulfur dioxide, unreacted unsaturated material, and other volatileimpurities. It can also be readily washed and the removal of additionalimpurities is accomplished in this manner. I

Serial No. 8,755 filed February 16, 1948, now Patent No. 2,645,631,granted July 14, 1953, describes and claims the production of a solidheteropolymeric resin resulting from interreaction of sulfur dioxide anda monoolefinic organic material which comprises conducting the reac tionwith the reactants dispersed in an aqueous emulsion.

By coagulation methods heretofore used, the resin is obtained in a, veryfinely divided form, which is a powder when recovered from the latex.Often this material is so finely divided as to make it very difficult tohandle it, since it frequently clogs available filters, or to purify itby washing or other treatment. In addition, since the sulfur dioxide ispresent to an appreciable extent in the aqueous phase, this is acidicand it is necessary to employ selected emulsifying agents which areeffective at low pH, such as long chain alkyl sodium sulfates and thebranched chain aliphatic or aromatic sodium sulfonates. However, laticesproduced using these emulsifying agents are very stable and difficult tocoagulate. Methods of coagulating with brine and/or a mineral acidordina-rily fail to coagulate sulfur dioxide resin latices containingthese selected emulsifying agents. Such coagulants may be successfullyemployed in these systems if unusually large quantities are employed,but economic considerations preclude the use of such quantitiesindustrially. Heretofore, the usual method employed for coagulatingsulfur dioxide resin latices has been by treatment with a brine-alcoholmedium by which method is obtained a satisfactory finely dividedcoagulum. However, since this method requires rather large amounts ofalcohol, the additional cost of providing and operating a recoverysystem for removing the alcohol from the serum must be borne. Further,an appreciable additional expense is represented by the alcohol left inthe wet coagulum and lost during the drying of the polymer.

I have now discovered a rapid, economical process for coagulating resinlatices produced by the emulsion polymerization of an unsaturatedorganic material and sulfur dioxide, herein generally referred to, forconvenience, as sulfur dioxide resins, particularly those in whichsurface active organic sulfates and sulfonates are present asemulsifying agents. By a preferred embodiment of my invention arelatively small quantity of a water-soluble salt of a polyvalent metalis employed as coagulant. The coagulation is effected rapidly andcompletely by causing the latex and a polyvalent metal salt or itsaqueous solution to be mixed with agitation. By suitably correlating thetemperature of the coagulation with the specific sulfur dioxide resinbeing coagulated, and controlling the coagulation temperature, agranular product of a controlled, or of a desired, particle size can beproduced.

An object of my invention is to produce a granular resin from sulfurdioxide and an unsaturated organic material.

Another object of my invention is to coagulate aresin from a latex.

A further object of my invention is to control the particle size of asulfur dioxide-unsaturate resin roduced by emulsionheteropolymerization.

Further objects and advantages of my invention will become apparent, toone skilled in the art, from the accompanying disclosure and discussion.

I have found that a critical factor of my in vention is the temperaturerange in which the coagulation is effected, and this range is differentfrom each particular resin. The proper temperature for coagulationappears to be connected with the softening or melting temperature of theresin, which is best identified as the minimum molding temperature ofthe resin. When the coagulation temperature is no more than a fewdegrees below this temperature, the resin particles agglomerate intolarge, unmanageable masses. A workable crumb, or coarse powder, isobtained from 15 to 50 F. below the minimum molding temperature of theresin. If too low a temperature is employed the coagulum is alwaysobtained in the form of extremely fine particles instead of the desiredcoarser crumb-like coagulum. On the other hand, if too high atemperature is employed the latex coagulates in the form of undesirablylarge lumps or as a single mass. Broadly, the temperature range in whichthe sulfur dioxide resin latices are coagulated to obtain the desiredgranular coagula lies between about F. and about 275 F. The temperaturerange which applies to a specific sulfur dioxide resin is usually muchnarrower as, for example, the range from about 140 F. to 175 F.applicable in the coagulation of l-butenesulfur dioxide resin latex, andthe outside limits of 110 F. and F. applicable when coagulat ingl-octene-sulfur dioxide resin latex. The minimum molding temperatures ofthese two resins are 195 F. to 200 F. and about F. respectively. Theaverage minimum molding temperatures for other olefin-sulfur dioxideresins include 190 F. fora resin produced from a mixture of equalweights of 1butene and l-octene, 190 F. for the resin from l-pentene,220 F. for 2-pentene, F. for l-hexene, and 80 F. for i-dodecene. Thetemperature of coagulation should, therefore, be below the minimummolding temperature of the resin coagulated and so correlated with thisminimum molding temperature as to producea coarse granular material or acrumb, and not so much lower as to produce a fine powder or so near thisminimum molding temperature as to produce large, dense and coherentlumps or masses which cannot be easily crumbled. As a fine powder isusually meant a material having an average particle diameter less than10 microns, and as a mass which can be easily crumbled is one that canbe crumbled between the fingers. Somewhat more generally, powders whichare too fine will rapidly clog a usual filter, when an attempt is madeto filter the coagulated latex, and the noncrumbly mass resembles afused mass which requires substantially the same effort and apparatus tocrush as does the horn-like resin produced by polymerization of theunsaturate and sulfur dioxide in a homogeneous mass.

When the coagulation is carried out by the addition of a salt of amultivalent metal, it appears that the metal reacts with andprecipitates the emulsifying agent, thereby removing it from solutionand destroying its emulsifying efiectiveness. The salt used may be anywatersoluble salt of a metal in group II, group IIIB, or group IVB ofthe periodic table, as set forth in "Modern Inorganic Chemistry, by J.W. Mellor (Longmans Green & 00., 1939), page 118; and particularlyeffective are salts of aluminum, calcium, magnesium, lead, strontium andbarium.

Although it is usually preferred to add the salt of such a polyvalentmetal in the form of its aqueous solution, according to my invention, asolid coagulant also may be employed to produce satisfactory resultswhen properly handled. When an aqueous solution'is employed, theconcentration of the coagulant solution may be as low as one weight percent or less or as high as saturation permits, although concentrationsfrom 1 to 15 weight per cent are usually preferred. The amount ofcoagulant employed in my process lies in the range from 90 to 250* percent of the Weight stoichiometrically required to react with all theemulsifying agent present. It is an important advantage of my processthat the said amount or" coagulant required is much smaller than theamount of coagulant required in processes employing a brine-acid orbrine-alcohol medium.

The sulfur dioxide resin latices produced using organic sulfate andsulfonate emulsifying agents are particularly applicable in myinvention. Examples of these compounds are the long chain alkyl sulfatesand sulfonates, the alkaryl sulfonates, and the sulfated and sulfonatcdesters, amides and amines. Specific compounds include sodium tetradecanesulfonate, sodium lauryl sulfate, sodium dodecyl benzene sulfonate,sodium dodecyl toluene sulfonate, sodium di-sec.-butyl naphthalenesulfonate, sodium diamyl sulfosuccinate and N-methyl-9-octadecenylamidosodium ethyl sulfonate commonly known as Igepon T.

In producing the sulfur dioxide resins, any one of a number ofunsaturated organic compounds may be used. Most of such reactants arethose which will react with sulfur dioxide to produce heteropolymericcompounds, under the other conditions heretofore employed by the priorart. Most of such reactants contain an oleiinic linkage, and may berepresented by the formula wherein R1 and R2 may be hydrogen, halogen,or alkyl, or R1 may be a constituent of a carbocyclic ring in which R4is a member, and R3 and R4 may be hydrogen, alkyl, alkenyl, aryl,aralkyl, or have an acetylenic linkage, or substituted groups thereofwherein substituents such as halo, nitro, hydroxyl, carbocyclic, cyano,and the like may be present, or R4 may be a constituent of a carbocyclicring in which R1 is also a member. In general the olefinic compoundemployed will not contain more than twenty carbon atoms per molecule.Examples of olefinic compounds which may be used include l-butene,Z-butene, propylene, isobutyl ne, pentenes, hex enes, cyclohexene,butadiene, styrene, alphamethyl styrene, alpha-chloro styrene, vinylacetylenes, vinyl chloride, vinyl bromide, and the like. It is alsofrequently desired to employ a mixture of olefinic compounds, ratherthan a single olefinic compound, in carrying out the process of thisinvention.

When operating according to the manner herein described it is generallyfound that substantially equimolar proportions of olefinic compound andsulfur dioxide react together. However, it is sometimes desired to use amolar excess of sulfur dioxide, say a 2:1 mol ratio of sulfur dioxide toolefinic material. In Examples 1, 2, 4 and 5 the mol ratio of sulfurdioxide to olefinic material was 1.7:1, and in Example 3 this ratio was2:1. In some cases it may even be desirable to use a higher ratio of theone reactant to the other, for example, a ratio of 5:1, or greater,depending upon operating conditions, olefinic material employed, amountof aqueous medium, etc., although it appears that, even in such cases,equimolar quantities of sulfur dioxide, and olefinic compound enter intoreaction. Frequently it will be desirable to remove the reactants fromthe reaction zone, and separate unrcacted materials, when between about'70 and about 97 per cent of the reactant present in the lesser amounthas reacted. When some diolefins are used as reactants, under someconditions, these materials tend to undergo homopolymerization to formrubber-like products; such reactions are undesired in this invention andconditions should be chosen with such diolefinic reactants, to inhibitsuch homopolymerization and favor joint interreaction to produceheteropolymeric resins.

Catalysts applicable in this process are the same as those which havebeen found effective when carrying out the reaction between olefiniccompounds and sulfur dioxide by methods heretofore employed. Examples ofthese catalytic materials include nitrates of the alkali metals andammonium, nitric acid, potassium persulfate, hydrogen peroxide, organicperoxides, such as cumene hydroperoxide, peracetic acid, and the like.The amount of catalyst used may vary over a wide range and will dependupon the material chosen. In cases where alkali metal nitrates orammonium nitrate are employed, the amount may vary from 0.03 to 0.60part per 100 parts reactants with an amount ranging from 0.15 to 0.45part being generally preferred. With other materials the quantity ofcatalyst used may be somewhat higher but in any event it is determinedby the case at hand.

Temperatures for carrying out the resin-producing reactions of thisinvention will usually fall within the range of about 10 to about 140F., with the narrower range 50 to B. being most frequently preferred.However, in some instances it may be considered advisable to employtemperatures below 10 F. in order to get a more satisfactory reaction.

Obviously when polymerizations are carried out in aqueous emulsion inthe absence of freezing point depressants, temperatures below thefreezing point of the acidic aqueous medium cannot be employed. The useof various additive agents, however, makes a process of the typedisclosed herein applicable at lower temperatures. An example of such alow temperature system is a glycerin-water solution, and the termaqueous emulsion should be construed to an clude the use of an aqueousmedium comprising water and a sufficient amount of a water-solublecomponent to lower the freezing point below the desired polymerizationtemperature, whether or not the actual polymerization temperature isabove or below freezing. It is generally preferred that the emulsion beof an oil in water type, with the ratio of aqueous medium to organicmonomeric material between about 1.511 and about 10:1, in parts byWeight. At low ratios the emulsions tend to have high viscosities and athigh ratios the yield per unit volume of reactor per unit of time islow. Inthe practice of the invention suitable means will be necessarytoestablish and maintain an emulsionand to remove reaction heat tomaintain a desired reaction temperature. The polymerization may beconducted in batches, semicontinuously, or continuously. The totalpressure on the reactants is preferably at least as great as the totalvapor pressure of the following recipe:

Parts by weight l-butene 46.7 Sulfur dioxide 88.3 Lithium nitrate 0.5Sodium di-sec.-butyl naphthalene sulfonate 4.0

Water 180.0

The reactants were emulsified in water and the mixture agitatedthroughout the reaction period while the temperature was held at 77 F.The reaction was stopped at the end of 2.5 hours, and the unreactedsulfur dioxide and olefin were vented from the latex. The latex,amounting to about 325 grams and containing about 4.5 grams of theemulsifying agent, was coagulated at room temperature (about 75 F.)Coagulation was accomplished by gradually adding about 210 millilitersof a one weight per cent solution of aluminum sulfate octadecahydratewhile agitating the latex. The coagulum was obtained in the form of auniform extremely fine, white precipitate.

Example 2 An olefin-sulfur dioxide resin latex was prepared by aqueousemulsion polymerization using the following recipe:

Parts by weight Water 180.0

The reactants were emulsified in water and the mixture agitatedthroughout the reaction period while the temperature was held at 77 F.The reaction was stopped at the end of 2.5 hours, and the unreactedsulfur dioxide and olefin were vented from the latex. The latex wasdivided into several 32.5 gram portions, each containing about 0.45 gramof the emulsifying agent, and each portion was coagulated with 21milliliters of a one weight per cent solution of aluminum sulfateoctadecahydrate. Each coagulation was effected at a differenttemperature; both the latex and the coagulant solution were brought tothis temperature before mixing. This resin has a minimum moldingtemperature of about 190 F.

The table lists the coagulation temperatures and shows the condition ofthe coagulum.

Temperature, F. Condition of Coagulum Single large dense mass.

One lump, crumbled easily.

Granular crumb.

Small particles, coarse powder.

VeryD small particles, fine powder.

Another resin latex, comprising the same resin 8. but also comprising aplasticizer, so that the minimum molding temperature was quite low,could be coagulated to produce a crumb only at a temperature below 45 F.

Example 3 A l-octene-sulfur dioxide resin latex was prepared by aqueousemulsion polymerization using the following recipe:

Parts by weight l-octene 63.6 Sulfur dioxide 71.4 Soluble ferricpyrophosphate 0.5 Sodium di-sec.-butyl naphthalene sulfonate 4.0 Water180.0

The reactants were emulsified in water and the mixture agitatedthroughout the reaction period while the temperature was held at 86 F.The reaction was stopped at the end of two hours, and the unreactedsulfur dioxide was vented from the latex. The latex was divided intoportions and coagulated with aluminum sulfate solutions at varioustemperatures as in Example 1. The table lists the coagulationtemperatures and shows the condition of the coagulum. The mini mummolding temperature of this resin is about F.

Temperature F. Condition of Coagulum Granular to large lumps.

Small particles to granular. Small particles.

Very small particles.

Example 4 A l-butene-sulfur dioxide resin latex was prepared by emulsionpolymerization using the following recipe;

Parts by weight l-butene 46.7 Sulfur dioxide 88.3 Lithium nitrate 0.5Sodium alkylbenzene sulfonate 5.0 Water 180.0

Milliliters of l0P Weight ercent coaglfl'mt Coagulant Solution EmployedMagnesium sulfate heptahydrate. 10 Aluminum chloride hexahydrate- 4Magnesium chloride hexahydrate 10 Calcium chloride 7 Potassium aluminumsulfate dodecylhydrate 6 Aluminum sulfate octadecahydrate 4 Emample 5 A1butene-sulfur dioxide resin latex was prepared by aqueous emulsionpolymerization using the following recipe:

Parts by weight l-butene 46.7 Sulfur dioxide 88.3 Lithium nitrate 0.5Sodium lauryl sulfate 5.0 Water 180.0

The reactants were emulsified in water and the mixture agitatedthroughout the reaction period while the temperature was held at 77 F.The reaction was stopped at the end of three hours, and the unreactedsulfur dioxide and olefin were vented from the latex. The latex washeated to 158 F., and was coagulated by addition of a weight per centaqueous solution of aluminum sulfate octadecahydrate. The coagulum wasof the desired granular or crumb-like form.

As will be evident to those skilled in the art, various modifications ofthis invention can be made, or followed in th light of the foregoingdisclosure and discussion, without departing from the spirit or scope ofthe disclosure or from the scope of the claims.

I claim:

1. An improved process for producing a granular heteropolymeric resinfrom l-butene and sulfur dioxide, which comprises copolymerizing same inthe presence of an aqueous emulsion and an emulsifying agent of theclass consisting of organic sulfate and sulfonate emulsifying agents,adding to the resulting resin latex at a temperature between 140 and 175an aqueous solution of aluminum sulfate in an amount between 90 and 250per cent by weight of that stoichiometrically equivalent to saidemulsifying agent, and recovering a resulting granular resin soproduced.

2. An improved process for producing a granular heteropolymeric resinfrom sulfur dioxide and an unsaturated organic compound which reactstherewith to form a heteropolymer, which coniprises copolymerizing saidreactants in the presence of an aqueous emulsion, coagulating aresulting resin latex at a temperature to 50 F. below the minimiunmolding temperature of said resin said temperature being such that thecoagulum is free from a hard dense mass of resin and said temperaturebeing above that at which a fine unfilterable resin powder is formed,and recovering a resulting granular resin so produced.

3. The process of claim 2 in which said resin is produced from l-buteneand sulfur dioxide and said temperature of coagulation is between 140and 175 F.

4. The process of claim 2 in which said resin is produced from l-octeneand sulfur dioxide and said temperature is between 110 and 130 F.

5. An improved process for producing a granular heteropolymeric resinfrom sulfur dioxide and an unsaturated organic compound which reactstherewith to form a heteropolymer, which comprises copolymerizing saidreactants in the presence of an aqueous emulsion, and an emulsifyingagent of the class consisting of organic sulfate and sulfonateemulsifying agents, adding to a resulting resin-latex at a temperature15 to 50 F. below the minimum molding temperature of said resin that thecoagulum is free from a hard dense mass of resin and above that at whicha fine unfilterable resin powder is formed, an aqueous solution of asalt of a metal of the class consisting of the metals in groups II,IIIB, and IVB of the periodic table in an amount be- 10 tween and 250per cent by weight of that stoichiometrically equivalent to saidemulsifying agent, and recovering a resulting granular resin soproduced.

6. The process of claim 5 in which said resin is produced from l-buteneand sulfur dioxide and said temperature of coagulation is between 140and 175 F.

7. The process of claim 5 in which said resin is produced from l-octeneand sulfur dioxide and said temperature is between and F.

8. The process of claim 5 wherein said metal is aluminum.

9. The process of claim 5 wherein said metal is calcium.

10. The process of claim 5 wherein said metal is lead.

11. The process of claim 5 wherein said metal is strontium.

12. An improved process for producing a granular heteropolymeric resinfrom 1-butene and sulfur dioxide, which comprises copolymerizing 1-butene and sulfur dioxide while said l-butene is dispersed in an acidicaqueous medium in the presence of a molar excess of sulfur dioxide at apolymerization temperature between 50 and 120 F. and in the presence ofan emulsifying agent of the class consisting of organic sulfate andsulfonate emulsifying agents, adding to a resulting resin latex at atemperature between and F. an aqueous solution of magnesium sulfate inan amount between 90 and 250 per cent by weight of thatstoichiometrically equivalent to said emulsifying agent, and recoveringa resulting granular resin so produced.

13. An improved process for producing an olefin-sulfur dioxide resin,which comprises copolymerizing sulfur dioxide and an olefin hydrocarbonhaving from four to eight carbon atoms per molecule while said olefin isdispersed in an acidic aqueous medium at a polymerization temperaturebetween 10 and 140 and coagulating a resulting resin latex at atemperature 15 to 50 F. below the minimum molding temperature of saidresin said temperature being such that the coagulum is free from a harddense mass of resin and said temperature being above that at which afine unfilterable resin powder is formed, and recovering a resultinggranular resin so produced.

14. In the recovery of a heteropolymeric resin produced bycopolymerization of sulfur dioxide with a normal butene dispersed in anaqueous medium in the presence of an emulsifying agent of the classconsisting of organic sulfate and sulfonate emulsifying agents whereby aresin latex is produced, the improvement which comprises adding to saidbutene-sulfur dioxide resin latex at a temperature between 140 and 175F. an aqueous solution of magnesium sulfate in an amount between 90 and250 per cent by weight of that stoichiometrically equivalent to saidemulsifying agent, and recovering a resulting granular resin soproduced.

15. In the recovery of a heteropolymeric resin produced bycopolymerization of sulfur dioxide with an unsaturated organic compoundwhich re- 7 cts therewith to form a heteropolymer, while said organiccompound is dispersed in an aqueous medium whereby a resin latex isobtained, the improvement which comprises coagulating said resin latexat a temperature 15 to 56 F. below the minimum molding temperature ofsaid resin, said temperature being such that the coagulum is free from ahard dense mass of resin and said temperature being above that at whicha fine unfilterable resin powder is formed, and recovering a resultinggranular resin so produced.

16. An improved process for producing a granular heteropolymeric resinfrom sulfur dioxide and an unsaturated organic compound which reactstherewith to form a heteropolymer, which comprises co-polymerizing saidreactants in the presence of an aqueous emulsion, and an emulsifyingagent of the class consisting of organic sulfate and sulfonateemulsifying agents, adding to a resulting resin latex at a temperaturein the range 15 to 50 F. below the minimum molding temperature of saidresin and such that the coagulum is free from a dense, hard mass ofresin and above that at which a fine unfilterable resin powder isformed, an aqueous solution of a salt of magnesium metal in an amountbetween 90 and 256 per cent by weight of that stoichiometricallyequivalent to said emulsifying agent, and recovering a resultinggranular resin so produced.

1'7. An improved process for producing an olefin-sulfur dioxide resin,which comprises copolymerizing sulfur dioxide and an olefin hydrocarbonhaving from four to eight carbon atoms per molecule while said olefin isdispersed in an acidic aqueous medium in the presence of an emulsifyingagent of the class consisting of organic sulfate and sulfonateemulsifying agents at a polymerization temperature between and 140 F.,and coagulating a resulting resin latex at. a temperature to 50 F. belowthe minimum molding temperature of said resin, said temperature beingsuch that the coagulum is free from a hard dense mass of resin and saidtemperature being above that at which a fine unfilterable resin powderis formed, and recovering a resulting granular resin so produced, thesaid coagulation being efiected by addition to said latex of awater-soluble salt of a metal of the class consisting of the metals ingroups II, 1113 and WE of the periodic table in an amount between 90 and250 per cent by weight of that stoichiometrically equivalent to saidemulsifying agent.

18. A process for producing a heteropolymeric resin of controlledparticle size from sulfur dioxide and an unsaturated organic compoundwhich reacts therewith to form a heteropolymer, which comprises in thepresence of an aqueous emulsion copolymerizing said reactants andcoagulating a resulting resin latex at a raised temperature near theminimum molding temperature of the final resin but at a temperaturewhich is sufficiently below said minimum molding temperature that thecoagulum is free from a hard, dense mass of resin and above that atwhich a fine unfilterable resin powder is formed, and recovering aresulting granular resin so produced.

19. A process for producing a heteropolymeric resin of controlledparticle size from sulfur dioxide and an unsaturated hydrocarbon whichreacts therewith to form a heteropolymer, which comprises in thepresence of an aqueous emulsion copolymerizing said reactants andcoagulating a resulting resin latex at an elevated temperature near theminimum molding temperature of the final resin but at a temperaturewhich is sufiiciently below said minimum molding temperature that thecoagulum is free from a hard, dense mass of resin and above that atwhich a fine unfilterable resin powder is formed, and recovering aresulting granular resin so produced.

20. A process for producing a heteropolymeric resin of controlledparticle size from sulfur dioxide and an olefin hydrocarbon which reactstherewith to form a heteropolymer, which comprises in the presence of anaqueous emulsion copolymerizing said reactants and coagulating aresulting resin latex at an elevated temperature near the minimummolding temperature of the final resin but at a temperature which issuificiently below said minimum molding temperature that the coagulum isfree from a hard, dense mass of resin and above that at which a fineunfilterable resin powder is formed, and recovering a resulting granularresin so produced.

21. A process for producing a heteropolymeric resin of controlledparticle size from sulfur dioxide and an aliphatic monoolefinichydrocarbon which reacts therewith to form a heteropolymer, whichcomprises in the presence of an aqueous emulsion copolymerizing saidreactants and coagulating a resulting resin latex at an elevatedtemperature near the minimum molding temperature of the final resin butat a temperatur which is sufiiciently below said minimum moldingtemperature that the coagulum is free from a hard, dense mass of resinand above that at which a fine unfilterable resin powder is formed, andrecovering a resulting granular resin so produced.

2 A process for producing a heteropolymeric resin of controlled particlesize from sulfur dioxide and l-butene which reacts therewith to form aheteropolymer, which comprises in the presence of an aqueous emulsioncopolymerizing said reactants and coagulating a resulting resin latex atan elevated temperature near the minimum molding temperature of thefinal resin but at a temperature which is sufficiently below saidminimum molding temperature that the coagulum is free from a hard, densemass of resin and above that at which a fine unfilterable resin powderis formed, and recovering a resulting granular resin so produced.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,371,719 Starkweather Mar. 20, 1945 2,392,756 Mighton Jan. 8,1946 2,435,778 Gracia Feb. 10, 1948 253L403 Crouch Nov. 28, 1950

1. AN IMPROVED PROCESS FOR PRODUCING A GRANULAR HETEROPOLYMERIC RESINFROM 1-BUTENE AND SULFUR DIOXIDE, WHICH COMPRISES COPOLYMERIZING SAME INTHE PRESENCE OF AN AQUEOUS EMULSION AND AN EMULSIFYING AGENT OF THECLASS CONSISTING OF ORGANIC SULFATE AND SULFONATE EMULSIFYING AGENTS,ADDING TO THE RESULTLING RESIN LATEX AT A TEMPERATURE BETWEEN 140 AND175* F. AN AQUEOUS SOLUTION OF ALUMINUM SULFATE IN AN AMOUNT BETWEEN 90AND 250 PER CENT BY WEIGHT OF THAT STOICHIOMETRICALLY EQUIVALENT TO SAIDEMULSIFYING AGENT, AND RECOVERING A RESULTING GRANULAR RESIN SOPRODUCED.